Conventionally, in a sealing apparatus (oil seal) for sealing gas or liquid between two members that can rotate relative to each other, such as a crankshaft, a transmission, a differential gear and the like of a vehicle, as illustrated in FIG. 12, those provided with a circular ring body (slinger) 102 fixedly attached to one member 101 and an annular seal lip body 104 fixedly attached to another member 103, and in a configuration where the seal lip body 104 and a main surface portion 102a of the circular ring body 102 have sliding contact, are known (patent literature 1). The circular ring body 102 is made of a hard material such as a metal, and the seal lip body 104 is made of a flexible material such as a rubber material.
In this sealing apparatus, the sliding contact surface between the circular ring body 102 and the seal lip body 104 serves as a sealing portion 104a, and entry of oil or the like into the sealing portion 104a is blocked. Moreover, in this sealing apparatus, as illustrated in FIG. 13, by forming a spiral discharge groove 105 in the one main surface portion 102a of a circular ring body to exert a pump effect and by discharging oil from the sealing portion 104a, the sealing is achieved.
That is, as illustrated by an arrow r in FIG. 13, when the circular ring body 102 rotates relative to the seal lip body 104, the discharge groove 105 formed in the circular ring body 102 of this sealing apparatus, by having a spiral shape, discharges the oil in the outer peripheral side direction, away from the sealing portion 104a. 
It should be noted that when the circular ring body 102 and the seal lip body 104 relatively rotate in both directions, the discharge groove 105 is formed in a shape in which spiral shapes in both directions overlap and cross each other.